The Montblanc ballpoint 380 was, according to Collectible Stars, in total produced from 1971 to 1979, with three different versions existing. The dark-green variant was only made between 1971 and 1975 and is depicted on page 73 of the standard work. Thus the pen can be relatively precisely classified temporally. For an unambiguous assignment to the respective variant, a sharp photo of the writing instrument is helpful.